Circuit breaker



Jan. 1963 J. P. ELLSWORTH ETAL 3,073,926

CIRCUIT BREAKER 3 Sheets-Sheet 1 Filed Oct. 16. 1959 AV i Fig.2.

Jan. 15, 1963 J. P. ELLSWORTH ETAL 3, 73,9 6

CIRCUIT BREAKER Filed Oct. 16, 1959 3 Sheets-Sheet 2 Fig. 3

Fig. 4

WITNESSES mvEn'ToRs James PqEllsworth a 5K V Robrt- .F'lick WzZ AM Y aATTORN Y 1963 J. P. ELLSWORTH ETAL 3, 73, 6

CIRCUIT BREAKER 5 Sheets-Sheet 3 Filed Oct. 16. 1959 United StatesPatent This invention relates to circuit breakers and, moreparticularly, to circuit breakers which are manually opened and closedand which are opened automatically upon the occurrence of an overloadcurrent.

An object of the invention is to provide a multi pole circuit breakerembodying an improved trip mechanism.

Another object of the invention is to provide a multipole circuitbreaker embodying an improved thermally and magnetically responsive tripdevice wherein there is provided an armature for each pole unit andinsulating means connecting said armatures whereby said armatures andsaid insulating means function as a trip member common to all of thepole units.

Another object of the invention is to provide a multipole circuitbreaker embodying an improved thermally and magnetically responsive tripdevice having, for each pole unit, an armature with ambient temperaturecompensating means attached thereto, and insulating means rigidlyconnecting al' of the armatures as a common trip member so that movementof any one of the armatures efiects automatic tripping of all of thepole units.

In accordance with one embodiment of the invention, a multi-pole circuitbreaker is provided with a set of separable contacts and a trip devicefor each pole unit; Each trip device includes a bimetal element, amagnet, an armature and a compensating bimetal element. The bimetalelement is supported at one end and the magnet is attached to thebimetal element near the free end thereof. The armature is pivotallysupported having one side adjacent the magnet, and the compensatingbimetal is attached to the armature and extends adjacent the side of themagnet which is opposite the side which faces the armature. Thearmatures for all of the pole units are rigidly connected by insulatingmeans so that movement of any one of the armature-s will effect movementof all of the armatures and release of a trip arm which is latched byone of the armatures. Release of the trip arm effects automatic openingof all of the sets of separable contacts. Upon the occurrence of anoverload current below a predetermined value in any pole unit, thebimetal defiects and because of the engagement of the magnet with thecompensating bimetal element, the armature is pivoted effecting releaseof the trip arm and all of the circuit breaker pole units areautomatically opened with a time delay. The compensating bimetal effectscompensation for movement of the bimetal element in response to changesin ambient temperature. Upon the occurrence of an overload current abovethe predetermined value in any one pole unit, the armature is attractedto the magnet member to effect instantaneous release of the trip arm.

The bimetal element is connected to and supported by a terminalconductor that extends into the circuit breaker housing. The outer endof the terminal conductor is often physically moved during normalcircuit breaker use, especially when the terminal is being connected ordisconnected. It is importaant that the inner portion of the terminalconductor be positively positioned so that it cannot move to disturb thecalibration of the trip device. In the past this inner portion of theterminal conductor has been secured to the circuit breaker housing bymeans of a positioning screw.

3,073,926 Patented Jan. 15, 1963 Another object of this invention is toprovide a circuit breaker embodying improved positive positioning meansfor holding the terminal conductor in position.

Another object of this invention is to provide a circuit breakerembodying a positive positioning member having a resilient portionbiasing the terminal conductor against an inner surface of the breakerhousing to hold the conductor firmly in place.

A further object is to provide a circuit breaker embodying a positivepositioning member for exerting pressure against the terminal conductorto hold it in place in the circuit breaker which positioning member hasa bimetal portion that flexes upon being heated to strengthen theholding force of the positive positioning member.

The invention both as to structure and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description when read in conjunction with theaccompanying drawings.

In said drawings:

FIGURE 1 is a vertical sectional view illustrating one pole unit of atwo-pole circuit breaker embodying the principles of this invention;

FIG. 2 is a vertical sectional view similar to FIG. 1 showing the otherpole unit of the duplex circuit breaker;

FIG. 3 is a plan view with parts broken away of the circuit breakershown in FIGS. 1 and 2;

FIG. 4 is an elevational view of the common trip member of the two-polecircuit breaker of this invention;

FIG. 5 is an elevational view of the load terminal conductor for one ofthe pole units;

FIG. 6 is a view taken along the line VI-VI of FIG. 5;

FIG. 7 is an elevational view of the positive positioning member of oneof the pole units;

FIG. 8 is a view taken along line VIIIVIII of FIG. 7; and

FIG. 9 is an elevational view of a common trip member similar to thetrip member shown in FIG. 4, but modified for use in a three-polecircuit breaker.

Referring to FIG. 1 of the drawings, the ciruit breaker generallycomprises a two piece housing of molded insulating material including abase 11 and cover 13, a stationary contact 15 and movable contact 17 foreach pole of the breaker, an operating mechanism indicated generally at19 and a trip device indicated generally at 21. The hous ing is dividedsubstantially into two separate compartments by means of a barrier 23molded integral with the base 11, and barriers 24, 25 and 26. Thebarriers 24 and 26 are molded integral with the cover 13, and thebarrier 26 interlocks with the barrier 23 to substantially close anopening 28 between the compartments which opening exists so that thebreaker may be easily assembled.

The stationary contacts 15 for each of the two poles of the circuitbreaker are mounted on the inner ends of conducting members 27 which areintegral with plug-in connectors 29 supported in the base 11 of thecircuit breaker housing. The moving contact 17 for each pole unit isrigidly secured to a U-.haped switch or contact arm 31. Both of thecontact arms 31 (FIGS. 1 and 2) are operated to open and closedpositions by the single operating mechanism 19.

The operating mechanism 19 comprises an operating member 32 having anintegral operating lever 33, an overcenter spring 37 and a releasabletrip member 39. A single operating handle 35 (FIG. 1) is molded integralwith the operating member 32. The operating member 32 including thehandle 35 and the operating levers 33 for both poles of the breakercomprises a single member of molded insulating material so thatoperation of the handle 35 simultaneously moves both of the levers 33.

w The operating member 32 has a central bearing surface for pivotallysupporting the member in the barrier 26 (FIGS. 2 and 3). Bearingsurfaces 42 (only one being shown in FIG. 3) on the ends of the member32 are provided for pivotally supporting the ends of the member inrecesses in the side walls of the cover 13.

The releasable trip member 39 '(FIGS. 1 and 2) comprises a springsupport portion 47 for each of the poles of the breaker, each of whichis secured adjacent its pivot axis to a tie rod or cross bar 49 ofmolded insulating material for unitary pivotal movement. The tie rod 49is provided with end bearing portions 52 (FIG. 3) for supporting theends of the releasable trip member 39 in bearing supports in the sidewalls of the cover 13 and base 11. The spring support portion 47 for oneof the poles of the breaker extends toward the left (FIG. 1) and has alatch end 53 which is normally engaged and releasably held by a singlelatch element of the trip device 21 (to be later described) toreleasably hold both of the spring support portions 47 of the releasabletrip member 39 in operative position.

Each of the operating levers 33 is bifurcated and the spaced legs 55thereof are provided with notches 57 in which are seated and pivoted theouter or upper ends of the legs 59 of the U-shaped switch members 31.The switch members 31 are held in place by the overcenter operatingsprings 37 which are connected under tension between the switch members31 and the corresponding spring support portions 47 of the releasabletrip member 39. As shown in FIGS. 1 and 2, the springs 37 bias theswitch members 31 to the closed position.

The circuit breaker is opened manually by moving the handle 35 (FIG. 1)counterclockwise from the position in which it is shown in solid linesto the position in which it is shown in dot and dash lines. During thismovement the outer or upper ends of the switch arms 31 are carried overto the right of the line of action of the overcenter springs 37whereupon the springs move the switch arms to the open position with asnap action. The contacts are closed by reverse movement of the.operating handle 35, that is, from the position in which the handle 35is shown in dot and dash lines in FIG. 1 to the position in which it isshown in solid lines. During this movement, the outer or upper ends ofthe switch members 31 are moved over to the left of the line of actionof the overcenter springs which then move the switch members to theclosed position with a snap action.

An arc extinguisher 61 is disposed in a recess or arc chamber in thebase 11 for each pole of the breaker for quickly extinguishing the arcdrawn when the circuit is interrupted. The are extinguishers may be ofany suitable type, each of those shown comprising a series of spacedslotted plates of magnetic material into which the arc is drawn andquickly extinguished. The are gases for each pole are drawn into apassage 62 along the bottom of the base 11 and vented out the end of thehousing opposite the stationary contacts. 7

The circuit breaker is tripped open automatically upon release of thelatch end 53 of the trip member 39. As soon as the releasable tripmember 39 is released, the springs 37 for both poles of the breakerrotate the trip member 39 including the spring support portions 47 foreach pole, in a counterclockwise direction, until the trip member isarrested by its engagement near the latch end 53 of the extended springsupport portion 47 with a projection 97 molded integral with the base 11of the circuit breaker housing. This movement of the releasable tripmember 39 carries the line of action of the springs 37 for both poles ofthe circuit breaker over to the left of the pivots at 57 of theassociated switch members 31, and the springs '37 then move the switchmembers to the open position with a snap action. When the springs 37move overcenter, they act through the switch members 31 to move thehandle 35 toan indicating position between the on? and off positions,giving a visual indication, that both poles of the circuit breaker havebeen tripped open.

Before the contacts can be closed following an automatic openingoperation, it is necessary to reset and relatch the mechanism. This isaccomplish by moving the handle 35 and the operating member 32 to aposition slightly beyond the off position. During this movement the legs55 of the levers 33 engage a pin 65 in the releasable trip members 47and restore the entire releasable trip member 39 for both of the polesto the latched position. The contacts are then closed in the previouslydescribed manner by movement of the handle 35 and the levers 33 to theon position.

The trip member 39 is released, to effect automatic opening of thecontacts, by operation of the thermal magnetic trip device 21. The tripdevice 21 for each pole unit of the circuit breaker includes a bimetal67 which is welded or otherwise attached to the central portion 68 of aterminal conductor 69. A magnet 71 is secured to each bimetal 67adjacent the free end thereof. An armature 73 having a compensatingbimetal member 75 attached to the lower end thereof, is provided foreach pole unit. Each compensating bimetal 75 extends adjacent the sideof the magnet which is opposite the side which faces the armature 73.The armatures 73 for both of the pole units are rigidly connected byinsulating means 77 so that movement of any one of the armatures willeffect movement of all of the armatures and release of the trip arm 39which is latched by only one of the armatures. As best seen in FIGS, 1,'2 and 4, each of the armatures 73 is riveted to an insulating plate 77by means of rivets 79. The combination of the two armatures 73 and theinsulating connecting plate 77 will be hereinafter referred to as acommon trip member 80 because it moves as a unit to effect release ofthe trip member39 and automatic opening of the contacts for each of thepole units of the circuit breaker. Each of the armatures 73 has two arms83 extending from the sides thereof. The outer arms 83 of the armaturesare pivotally supported in V-shaped slots in metallic pivot plates 85(only one being shown in FIG. 1), and the common trip member 80 ispivotally supported thereby. As best illustrated in FIG. 3, the metallicpivot plates 85 are supported in notches in the insulating housing. Anopening 81 exists in the insulating plate 77 to provide electricalclearance between the inner arms 83 of the armatures 73. A spring 86disposed in a recess in the barrier 24 of the housing cover 13, biasesthe common trip member 80 in a counterclockwise direction.

When the circuit breaker is in the closed position, the circuit for eachpole unit extends from the plug-in connector 29 through the conductingmember 27, separable contacts 15 and 17, contact arm 31, a flexibleconductor 88 which is welded at one end to the contact arm 31 and at theother end to the bimetal 67, the bimetal member 67 to the terminalconductor 69.

As is best illustrated in FIG. 4, each of the armatures 73 has arectangular shaped opening 87 forming a lower ledge 89. The lower ledge89 of the armature on the left as viewed in FIG. 4, holds the latch end53 (FIG. 1) of the trip member 39 when the parts are in a latchedposition. Although only one of the armatures 73 actually supports thetrip member 39, they are of identical construction because they arestamped from the same die.

Upon the occurrence of an overload current below a predetermined valuein any pole unit, the bimetal 67 for that pole unit deflects to the leftas viewed in FIGS. 1 and 2, and an insulating button 91 on the magnet 71engages the compensating bimetal 75 for that pole unit, so that movementto the left of the bimetal 67 effects clockwise pivotal movement of thecommon trip member 80 and release of the trip member 39 to effectautomatic opening of the contacts for both of the circuit breaker poleunits.

The compensating bimetal 75 for each pole unit, is

provided to compensate for movement of the bimetal element 67 inresponse to changes in ambient temperature. The high expansion sides ofthe bimetals 67 and. 75 are on the right as viewed in FIGS. 1 and 2, sothat upon deflection of any of the bimetals 67 to the left in responseto a rise in ambient temperature, the bimetal 75 associated therewithwill deflect the same amount to the left providing that there will be nosubstantial unlatching movement of the common trip member 80 andtherefore no loss of latch engagement between the latch end 53 of thetrip member 39 and the latching surface. 89 of the armature 73. If theambient temperature should then drop the bimetal 67 deflects to theright and the bimetal 75 deflects to the right the same amount tocompensate for this movement of the bimetal element 67.

Upon the occurrence of an overload current above the predetermined valuein any one pole unit, the magnet member 71 for that pole unit, isenergized sufliciently to attract the armature 73 which is associatedtherewith, effecting clockwise movement of the common trip member 80 andinstantaneous release of the trip member 39 to effect automatic openingof the contacts for both of the pole units. A common magnet and coilarrangement may be attached to each bimetal 67 in place of each magnet71 to increase the speed of magnetic tripping as is well known in theart.

In each pole unit, the bimetal element 67 is welded or otherwiseattached at its upper end to the central portion 68 of the associatedterminal conductor 69 (FIGS. 5 and 6). The thermal tripping time isadjusted by means of a screw 72 (FIGS. 1, 2 and 3) in each pole unit,which threadedly engages a supporting member 66. The rounded inner endof the screw 72 applies a pressure to the central portion 68 of theterminal conductor 69. Turning the screw 72 varies the pressure appliedto the terminal conductor central portion 68 thereby varying theposition of the bimetal 67 in the associated pole unit. Variance of theposition of any of the bimetals 67, through the associated compensatingbimetal 75, effects variance of the amount of latch engagement betweenthe latch end 53 of the trip member 39 and the lower ledge or latchingsurface 89 of one of the armatures 73, and therefore, affects thethermal tripping time.

A connecting screw 70 is provided in each pole unit for connecting theterminal conductor 69 for that pole unit in an electric circuit. Theouter end of the terminal conlductor 69 is often physically moved duringnormal circuit breaker use especially when the terminal is beingconnected or disconnected. It is important that the inner portion of theterminal conductor 69 be positively positioned so that any movement ofthe outer portion will not be transmitted to the inner portion todisturb the calibration of the trip device 21 or to effect a falsetripping operation.

A positive positioning member 93 (FIGS. 7 and 8) is provided for eachpole unit of the circuit breaker. Referring to FIG. 3, the circuitbreaker insulating cover 13 has two slots molded integral therewith foreach of the pole units for receiving and supporting the positivepositioning member 93. The slots are not shown for the lower pole unitas viewed in FIG. 3, because the complete cover portion 13 is brokenaway for this pole unit. Referring to FIGS. 7 and 8, each of thepositive positioning members 93 has two outer leg portions 95 and 96,and a center portion 97 that is stamped to a position where it extendsout of the plane in which the two outer leg portions are disposed (FIG.8). The leg portion 96 is cut away at 98 to provide electrical clearancebetween the pole units. The stamped out center portion 97 for each ofthe positioning members 93, is resilient and flexible so that when theparts are in place, the resilient portion 97 biases against theassociated terminal conductor 69 forcing the conductor 69 against twoinner surfaces 99 (FIG. 3) molded integral with the circuit breakercover 13. There are two inner surfaces 99 molded with the cover 13 foreach pole unit; but as viewed in FIG. 3, the surfaces 99 can be seenonly in the upper pole unit because the cover 13 is broken completelyaway for the lower pole unit. An upper wedging portion 101, of eachpositioning member 93, is provided to bias against the central portion68 of the associated terminal conductor 69 to force the central portion68 against the associated adjusting screw 72. When the parts are inplace, the biasing forces of the resilient portion 97 and the wedgingportion 191, of each positioning member 93 against the associatedterminal conductor 69, provide that the inner portion of that terminalconductor 69 will be stationary, and that the calibration of the tripdevice 21 will not be disturbed even when the circuit breaker is beingconnected or disconnected.

In a modification of the positioning member 93, the center portion 97thereof, is bimetallic. Upon being heated by current flowing through theterminal conductor 69, the bimetal portion 97 of the modifiedpositioning member 93, flexes increasing the bias against the terminalconductor 69 to assure more positive positioning when current is flowingthrough the circuit breaker.

While a two-pole circuit breaker has been specifically described, athree-pole breaker is readily provided by making a housing having threecompartments instead of the two compartments shown and adding anotherpole unit like the one shown in FIG. 2. The extended trip arm 47 withthe latching portion 53 thereon, would be positioned preferably in thecenter pole. FIG. 9 illustrates a common trip member for use in athree-pole breaker. This common trip member indicated generally atcomprises three armatures 73 connected to function as a unit by twoinsulating plates 77' which plates are riveted at 79 to the armatures73. Each of the armatures 73 has a bimetal member 75' attached thereto.The two outer arms 83 are provided to pivotally support the common tripmember 80 on metallic side plates which are not shown; but which areidentical in construction to the plate 85 of FIG. 1. The operation ofthe three-pole circuit breaker is substantially the same as thespecifically described operation of the two-pole circuit breaker.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe structural details and arrangement of par-ts thereof may be madewithout departing from the spirit of the invention.

We claim as our invention:

1. A multipole circuit breaker comprising, in combination, a set ofseparable contacts for each pole unit, latched means common to all ofsaid pole units and releasable to effect automatic separation of all ofsaid sets of contacts, a metallic pivot supported at each side of saidcircuit breaker, a common trip member pivotally supported by saidmetallic pivots and latching said latched releasable means, meansbiasing said common trip member to a latching position, said common tripmember comprising an armature for each of said pole units and insulatingmeans rigidly connecting said armatures, portions of the outer or" saidarmatures engaging in said metallic pivots to pivotally support saidcommon trip member, magnetic means for each of said pole unitsassociated with each of said armatures, and the magnetic means for anyone of said pole units upon energization by an overload current above apredetermined value attracting the armature associated therewith causingsaid common trip member to pivot against the bias of said biasing meansto release said latched releasable means.

2. In a circuit breaker, an enclosing housing of molded insulatingmaterial, a circuit breaker mechanism enclosed by said housingcomprising separable contacts and means releasable to eflect automaticseparation of said contacts, a terminal conductor extending into saidhousing and along an inner surface of said housing, a tripping membersupported by said terminal conductor and moving to effect release ofsaid releasable means, a positive positioning member, means supportingsaid positive positioning member within said housing, and said positivepositioning member having a resilient portion engaging and biasing saidterminal conductor against said inner surface to positively positionsaid terminal conductor.

3. A circuit breaker including, in combination, an enclosing housing ofmolded insulating material, a circuit breaker mechanism within saidhousing comprising relatively movable contacts and means releasable toeffect automatic opening of said contacts, a terminal conductorextending into said housing and along an insulating surface in saidhousing, a tripping member supported by said terminal conductor andmovable to effect release of said releasable means, a positioning memberhaving a resilient portion thereon, means molded integral with saidhousing defining slots within said housing, said slots receiving andsupporting said positioning member, and said resilient portion engagingsaid terminal conductor and exerting pressure against said terminalconductor to prevent movement of said terminal conductor within saidhousing.

4. A circuit breaker comprising, in combination, a housing of moldedinsulating material, a circuit breaker mechanism enclosed by saidhousing comprising separable contacts and means releasable to effectautomatic separation of said contacts, a terminal conductor extendinginto said housing along an inner surface of said housing, armaturesupported within said housing and movable to eiiect release of saidreleasable means, a bimetal member attached at one end to said terminalconductor and having the other end free, a magnet member attached tosaid bimetal member adjacent the free end thereof, said magnet memberupon energization by overload currents above a predetermined amountattracting said armature causing said armature to move and effectrelease of said releasable means, said bimetal member in response tooverload currents below said predetermined amount bending to effectmovement of said armature to effect release of sa d releasable means, apositioning member having a resilient portion thereon, means moldedintegral with said housing defining slots in. said housing, said slotsreceiving and supporting said positioning member, and said resilientportion engaging said terminal conductor and biasing said terminalconductor against said inner surface to prevent movement of saidterminal conductor within said housing.

5. A circuit breaker including, in combination, an onclosing housing ofmolded insulating material, a circuit breaker mechanism within saidhousing comprising relatively movable contacts and means releasable toeffect automatic opening of said contacts, a terminal conductorextending into said housing and along an insulating surface in saidhousing, a tripping member supported by said terminal conductor andmovable to effect release of said releasable means, a positioning memberhaving a bimetal portion thereon, means molded integral with saidhousing defining slots within said housing, said slots receiving andsupporting said positioning member, said bimetal portion engaging saidterminal conductor and exerting pressure against said terminal conductorto prevent movement of said terminal conductor within said housing, andsaid bimetal portion upon being heated bending and increasing thepressure exerted against said terminal condoctor. a

6. A circuit breaker comprising, in combination, a rousing of moldedinsulating material, a circuit breaker mechanism enclosed by saidhousing and comprising separable contacts and means releasable to eiectautomatic separation of said contacts, a terminal conductor extendinginto saidhousing along an inner surface of said housing, an armaturesupported within said housing and movable to effect release of saidreleasable means, a bimetal member attached at one end to said terminalconductor and having the other end free, a magnet member attached tosaid bimetal member adjacent the free end thereof, sai

magnet member upon energization by overload currents above apredetermined amount attracting said armature causing said armature tomove and effect release of said releasable means, said bimetal member inresponse to overload currents below said predetermined amount bending toeffect movement of said armature to eilect releas of said releasablemeans, a positioning member having a resilient bimetal portion thereon,means molded integral with said housing defining slots in said housing,said slots receiving and supporting said positioning member, and saidresilient bimetal portion engaging said terminal conductor and biasingsaid terminal conductor against said inner surface to prevent movementof said terminal conductor within said housing, and said bimetal portionupon being heated flexing and increasing the bias exerted against saidterminal conductor.

7. In a multipole circuit breaker, an enclosing housing of moldedinsulating material, a multipole circuit breaker mechanism enclosed bysaid housing, said multipole circuit breaker mechanism comprising a setof separable contacts for each pole unit, means releasable to effectautomatic separation of all of said sets of contacts, a trip membercommon to all of said pole units and movable to release said releasablemeans, said common trip member comprising an armature for each of saidpole units and insulating means connecting said armatures, a trippingmember for each pole unit having magnetic means thereon for attractingthe armature in the same pole unit to effect movement of said commontrip member and release of said releasable means, a terminal conductorfor each pole unit extending into said insulating housing, each of saidtripping members being supported by the terminal conductor which ispositioned in the same pole unit, a positive positioning member for eachof said pole units, means supporting said positive positioning memberswithin said housing, and each of said positive positioning membershaving a resilient part engaging and biasing the terminal conductor inthe same pole unit against an inner surface of said housing topreventmovement within said housing of the terminal conductor in thesame pole unit.

8. A multipole circuit breaker comprising in combination, a set ofseparable contacts for each pole unit, latched means common to all ofsaid pole units and releasable to efiect automatic separation of all ofsaid sets of contacts, a metallic pivot supported at each side of saidcircuit breaker, a common trip member pivotally supported by saidmetallic pivots, said common trip member comprising an armature for eachof said pole units and insulating means rigidly connecting saidarmatures, portions of the outer of said armatures engaging in saidmetallic pivots to pivotally support said common trip member, means onone of said armatures latching said latched releasable means, meansbiasing said common trip member to a latching position, magnetic meansfor each of said pole units associated with each of said atmatures, andthe magnetic means for any One of said pole units upon energization byan overload current about a predetermined value attracting the armatureassociated therewith causing said common trip member to pivot againstthe bias of said biasing means to release said latched releasable means.

References Cited in the file of this patent UNITED STATES PATENTS2,656,437 Allen Oct. 20, 1953 2,677,025 Dyer Apr. 27, 1954 2,776,349Thomas Jan. 1, 1957 2,798,918 Gelzheiser July 9, 1957 2,811,607 DorfmanOct. 29, 1957 2,889,428 Kingdon et al. June 2, 1959 2,904,655 GelzheiserSept. 15, 1959

1. A MULTIPOLE CIRCUIT BREAKER COMPRISING, IN COMBINATION, A SET OFSEPARABLE CONTACTS FOR EACH POLE UNIT, LATCHED MEANS COMMON TO ALL OFSAID POLE UNITS AND RELEASABLE TO EFFECT AUTOMATIC SEPARATION OF ALL OFSAID SETS OF CONTACTS, A METALLIC PIVOT SUPPORTED AT EACH SIDE OF SAIDCIRCUIT BREAKER, A COMMON TRIP MEMBER PIVOTALLY SUPPORTED BY SAIDMETALLIC PIVOTS AND LATCHING SAID LATCHED RELEASABLE MEANS, MEANSBIASING SAID COMMON TRIP MEMBER TO A LATCHING POSITION, SAID COMMON TRIPMEMBER COMPRISING AN ARMATURE FOR EACH OF SAID POLE UNITS AND INSULATINGMEANS RIGIDLY CONNECTING SAID ARMATURES, PORTIONS OF THE OUTER OF SAIDARMATURES ENGAGING IN SAID METALLIC PIVOTS TO PIVOTALLY SUPPORT SAIDCOMMON TRIP MEMBER, MAGNETIC MEANS FOR EACH OF SAID POLE UNITSASSOCIATED WITH EACH OF SAID ARMATURES, AND THE MAGNETIC MEANS FOR ANYONE OF SAID POLE UNITS UPON ENERGIZATION BY AN OVERLOAD CURRENT ABOVE APREDETERMINED VALUE ATTRACTING THE ARMATURE ASSOCIATED THEREWITH CAUSINGSAID COMMON TRIP MEMBER TO PIVOT AGAINST THE BIAS OF SAID BIASING MEANSTO RELEASE SAID LATCHED RELEASABLE MEANS.